The tasks he's doing aren't particularly skilled and most people would be fairly capable of doing them themselves if they had the time/inclination.

I admit, though, I've never lived in NYC, so my estimation is likely off. Even in Phoenix, there were plenty of migrant workers driving down the prices for manual labor.

You know the job better than any of us. If you feel that he needs to be paid more and you can, then go ahead and do so